Device Names Change Unexpectedly

NNM’s periodic configuration checking occasionally turns up a device name change. This is a configuration alarm. As such, it represents a nugget of useful information. NNM determines the selection name of an IP addressable device as follows:

• the DNS name corresponding to the lowest IP address, otherwise

• the MIB-2 system name if the device supports SNMP, otherwise

• the IP address if there is one, otherwise

• the device MAC address (assuming layer 2 discovery is on)

A typical device name change often corresponds to a change in the DNS database. The IP address inverse DNS lookup previously returned the original device name, but now it returns some other name. This may be completely legitimate or it may be an administrative error. Another typical device name change is that the name reverts to the IP address of the device. This usually happens when the device entry is removed from the DNS database and the device does not support SNMP. Otherwise, the device name would revert to that specified in the MIB-2 system group.